“These are the generations of the heavens and of the earth when they were created, in the day that the LORD God made the earth and the heavens,” (Genesis 2:4, KJV)
The KJV, as with most other translations, uses “LORD” (in all capital letters) to refer to the covenant name of God. The Hebrew word is “יהוה” (YHWH), which is called the Tetragrammaton. The Jews refrained from pronouncing this sacred name lest they accidentally take God’s name in vain. These Jews adopted the practice of reading the Tetragrammaton as “Adonai”, which is the Hebrew word for “Lord”. While some critics claim that this was just a peculiar practice of Judaism, Jesus himself adopted this practice. Whenever Jesus quoted Old Testament passages that have the Tetragrammaton, he translated the Hebrew “יהוה (YHWH)” as “kurios,” which is the Greek word for “Lord.” Thus Jesus used either an Aramaic or Greek word for “Lord” to translate “יהוה.” At the very least, the New Testament writers used “kurios” to refer to the Tetragrammaton. Here are some examples:
In Matthew 4:7, Jesus quoted Deuteronomy 6:16. The Hebrew in Deuteronomy 6:16 says, “יהוה אלהיכם (YHWH elohei-chem).” The Greek translation of this in Matthew 4:7 is “κυριον τον θεον σου (kurion ton theon sou).”
In Matthew 21:42, Jesus quoted Psalm 118:22-23. The Hebrew in Psalm 118:23 says, “יהוה (YHWH).” The Greek translation of this in Matthew 21:42 is “κυριου (kuriou).”
In Luke 20:42, Jesus quoted Psalm 110:1. The Hebrew of Psalm 110:1 says, “יהוה לאדני (YHWH l’adoni).” The Greek translation of this in Luke 20:42 is “ο κυριος τω κυριω μου (ho kurios to kurio mou).”
The LXX, the ancient Greek translation of the Hebrew Bible, also translates “יהוה אלהים (YHWH Elohim)” as “κύριος ὁ θεὸς (Kurios ho Theos).” If Greek-speaking Jews, early Christians, and our Lord himself translated YHWH as the word for “Lord” in their respective languages, then we too in English can translate YHWH as “LORD.” If we are supposed to translate YHWH as “Jehovah” or “Yehovah” at all times, then these forms of the Tetragrammaton should appear at least once in the New Testament. They do not. While some claim that all of the extant New Testament manuscripts are corrupted, and that the originals had “Jehovah”, there is absolutely no evidence of such unanimous corruption.
Lastly, the very reason that the Tetragrammaton even came to be pronounced as “Jehovah” is because the the Jews pronounced the name as “Adonai” (Lord). Since the Tetragrammaton consists of consonants only, the vowels which were added were taken from the three vowels of “Adonai” (the “i” in Adonai is actually a consonant (Yod) in Hebrew). JHVH (the Latin form of YHWH) became JaHoVaH, which eventually permutated into English as “Jehovah”. Thus it makes no sense to say that YHWH should never be read as “LORD” but only as “Jehovah”, because the name “Jehovah” would not have arisen if it were not for Jews reading YHWH as “LORD”.